Thermal Regime of Permafrost in Tian Shan Mountains from Large Ensemble Numerical Simulations at 1 km2 Scale

In this study, we incorporated a degree-day-based bulk snow scheme into the Flexible Permafrost Model (FPM) to simulate the ground thermal regime over the Tian Shan Mountains (TSM). To account for uncertainties in meteorological forcings and model parameters, we conducted 50-member large ensemble simulations. The model was driven by two distinct reanalysis datasets, ERA5 and JRA3Q, with 25 ensemble members generated for each forcing. This dataset provides physically consistent, high-resolution permafrost characteristics across the TSM, including the active layer thickness, mean annual ground temperature at 3, 5, 10, 15 and 20 m depth, and the permafrost extent.